Pathogenesis: Complete obstruction of the lacrimal duct, inferiorly by non-permeability of the valve of Hasner, and superiorly by a valve mechanism at the valve of Rosenmüller.

Associated anomalies: None. The cyst may produce deformities of the inferior turbinate and even of the septum.

Differential diagnosis: Frontonasal meningocele, potentially also hemangioma, dermoid cyst, mucocele from cystic fibrosis, although these are either unlikely in the age group, or have a different echotexture.

Prognosis: Excellent.

Recurrence risk: Unknown.

Management: External digital pressure on the cyst may enable the contents to decompress through the nose. If this is unsuccessful, probing of the nasolacrimal duct (from the eye towards the nose) with inferior turbinate outfracturing may establish patency of the valve of Hasner. In rare cases this is still inadequate, and marsupialization (dacryocystorhinostomy) of the nasal component with silicone stenting is performed.

Introduction

The prenatal diagnosis of a distended lacrimal sac—a dacryocysto­cele— is simple because of its characteristic appearance and position. The condition should be known since it is a benign anomaly, and the parents can be reassured as to the outcome of the pregnancy. We present a case of dacryocystocele detected at 34 weeks gestation.

Case report

A 37-year-old woman G5P3 was referred for an ultrasound examination due to premature rupture of membranes. Her prenatal care had been with a midwife and a home birth had been planned. No previous ultrasound exams had been performed. The examination revealed a 1 cm cystic mass inferior to the left medial canthus (figs. 1, 2).

Fig. 1: Axial section that demonstrates the globe, the dacryocystocele (arrow) and the nose.

Fig. 2: Coronal section that demonstrates the eye, the dacryocystocele (arrow), the nose and the mouth.

No associated anomalies of the intracranial or facial structures were apparent. The amniotic fluid volume was normal for 34 weeks gestation.The orbits appeared symmetrical. Twenty-seven days after premature rupture of membranes, a 3171g-baby girl was born by spontaneous vaginal delivery with tachypnea. On clinical examination, a bluish mass was noted in the left medial canthus. The cyst resolved spontaneously three days after birth.

Discussion

This is a rare clinical condition and only the second in utero observation of a dacryocystocele in the world literature2.

Embryology

In the 7 mm embryo, a thickened ridge followed by an infolding of the ectoderm occurs at the naso-optic fissure (fig. 3)3. The ectoderm sinks into the mesoderm until it forms an ectodermal epithelial cord in the 12 mm embryo. This column is oriented from the medial canthus to the anterior third of the inferior turbinate. As the column extends, it bifurcates in its cranial portion (fig. 4 left). The two outpouchings develop and become the superior and inferior canaliculi (fig. 4 right).

Fig. 3: In the 7 mm embryo, a thickened ridge followed by an infolding of the ectoderm occurs at the naso-optic fissure.

Fig. 4: The ectodermal epithelial cord is oriented from the medial canthus to the anterior third of the inferior turbinate. As the column extends, it bifurcates in its cranial portion to become the superior and inferior canaliculi and canalize from the most cephalic part downwards.

Fig. 5: The normal anatomy compared to the dacryocystocele.

The lacrimal duct anlage vacuolize from the most cephalic part downwards towards the nasal end at the inferior turbinate. The canalization process creates the lacrimal duct during the third month. The junction between the lacrimal duct and the nasal epithelium may exist after six months, but is not always established by birth.

The intervening membrane (which will become the valve of Hasner after perforation) is responsible for the obstruction of the lacrimal duct, which is manifested in the newborn by epiphora. Since tears are not usually produced at birth, the obstruction is rarely symptomatic early, and by the time it could become symptomatic, the patency of the valve of Hasner is usually established.

The canaliculi perforate the eyelids on the ocular surface, and the opening is called the punctum. More distally,the canaliculi usually join before entering the lacrimal sac. The duct that results from the fusion of the canaliculi is called the sinus of Maier or common canaliculus, and it connects to the lacrimal sac at the valve of Rosenmüller.

Pathogenesis

When the sinus of Maier is absent, the superior and inferior canaliculi enter the lacrimal sac independently and at a hyperacute angle. This occurs in approximately 10% of normal infants and may predispose to kinking, creating a valve effect4.

An non patent valve of Hasner (distal lacrimal drainage system) is a prerequisite for the formation of a dacryocystocele, and may exist in up to 73% of normal term infants3.

When this valve mechanism coexists with an inpatent valve of Hasner, the stage is set for the development of a dacryocystocele: fluid that is squeezed by the blinking motion enters the lacrimal sac, but cannot exit4. The lacrimal sac can easily expand in the medial canthal region since there is no bony or tendinous structure to directly limit its expansion, and since its wall is made of a respiratory epithelium.

The origin and composition of the sac contents have been discussed for years in the ophthalmic literature. This case supports the theory that the fluid in the dacryocystocele is amniotic fluid since the tear secretion normally is not significant until 3 to 4 weeks postpartum5. However, because of the viscous nature of the sac contents, some authors have proposed that it could represent mucus produced by the intraluminal goblet cells6.

Diagnosis

The prenatal diagnosis is made by the detection of a purely cystic mass inferomedial to the eye, with no associated anomalies. The dacryocystoceles shown in the litterature have all been smaller than the size of the globe. The extension of the cyst into the nose could potentially be demonstrated by the visualization of an enlarged lacrimal duct in the maxillary bone, and a second and smaller nasal cyst below the inferior turbinate. Similar findings have been demonstrated in newborns by CT7, 8.

Prevalence

The number of cases reported in the literature is small: fewer than 40 cases2, 7-14. Unfortunately, the only reference in the prenatal literature has incorrectly stated that the disorder is common2. This unfortunate error resulted from a confusion between dacryostenosis (a common anomaly, as mentioned above) and dacryocystocele (an uncommon anomaly).

Associated anomalies

No associated anomalies have been described. Consequential anomalies include an enlarged lacrimal duct in the maxilla and lacrimal bone, medial deviation of the inferior turbinate, and more rarely of the nasal septum. Rarely, the appearance of hypertelorism is produced by the extra soft tissue medial to the eye8.

Differential diagnosis

The differential diagnoses mentioned in the literature include frontonasal meningocele (or cephalocele), hemangioma, and dermoid cyst9, 11, 13, 17. Hemangioma and dermoid cysts are rarely purely cystic by ultrasound and should seldom be considered in the differential diagnosis. Frontonasal meningocele are associated with more severe disorganization of the face with displacement of the eye, nose or mouth. Mucoceles in cystic fibrosis have not been reported in the newborn, and they affect the paranasal sinuses16.

Prognosis

Congenital dacryocystocele is a benign condition. There is no predisposition to the development of a secondary facial anomaly. Once corrected, whether spontaneous, medical or surgical, the infant will have a normally functioning naso­lacrimal drainage system.

Recurrence risk

The large majority of infants (71%) treated will never reaccumulate material in their lacrimal sac10. If the dacryocystocele reforms, a repeat probing is highly successful. Rarely, someinfants will need a more definitive surgical procedure: dacryocystorhinostomy. The recurrence risk in subsequent pregnancies is unknown.

Clinical presentation

The infant encounters no clinical signs of epiphora (tearing) or dacryocystitis (infection). The only clinical finding is that of a bluish mass below the medial canthal tendon. Thus, the condition typically is not brought to the attention of a pediatrician or ophthalmologist. The dacryocystocele is typically sterile since colonization of the lacrimal drainage system is usually not established until the first several weeks of life. When infected, the most common bacteria isolated are Staphylococcus organisms9.Resolution—as in our case—by spontaneous opening of the distal lacrimal drainage system may occur during the first few weeks of life before bacterial colonization and significant tear production commence. This may explain why this condition is not reported more frequently.

Management

If external digital pressure is not immediately successful, then early nasolacrimal probing with inferior turbinate outfracturing is the treatment of choice15. Dacryocystocele and dacryocystitis benefit from early probing11. This is in contrast to the usual conservative measures of warm compresses, downward massage and antibiotics used for all other neonatal lacrimal system disorders. By relieving the obstruction, atony of the sac and disruption of the medial canthal musculature and skin are prevented, preserving the lacrimal pump mechanism. Furthermore, if left unaltered, the fluid-filled sac is at a higher risk of infection, secondary scarring and permanent closure, requiring a more involved surgical “bypass” procedure termed a dacryocysto­-rhinostomy.